John w



(No Model.)

J. W. BARRON.

PatentedJan. 13, 1885.

Wife doa-l TINTTEE STaTEs PATENT EETEEC1 JOHN W. BARRON, OF BOSTON,MASSACHUSETTS, ASSIGNOR TO EDVARD F.

HAGAR, OF SAME PLAGE, AND HENRY SAVYER, OF CHELSEA, MASS.

ZINCOGRAPHY.

SPECIFICATION forming part of Letters Patent No. 310,638, dated January13, 1885.

A pplication filed January 7, 1884.

.that the ink is liable to adhere to the larger depressed or opensurfaces between and around the printing lines or surfaces on the plate,the moisture applied by the damping-roller before the application of theink being incapable of protecting said surfaces from the printing-inkunless mixed with an astringent such as nutgall, which is objectionable,because it attacks the material in which the design is formed onl theplate and renders the plate incapable of producing as many impressionsas it would do if no astringent were used. These difficulties haveheretofore made zincography impracticable for the production of picturesor designs having any considerable open spaces between and around thelines composing the picture or design, and the process has thereforebeen confined chiefly to the production of such pictures or designs ashave no extended open or unprinted surfaces within the limits of thezinc plate.

My invention has for its chief object to provide means whereby thelarger open surfaces between and around the printing lines or surfacesmay be protected, so that the printingink will not adhere to them, andto this end it consists in perforating said open surfaces to form smallorifices extending through the plate, and supplying said orifices withan absorbent which will receive water from lthe damping-rolls and allowsaid water to ooze out under the pressure of the inking-roller, thusinsuring a sufficient lm of water between the inking-roller and thesurfaces surrounding said perforations to prevent the ink from adheringto said surfaces, the perforations being minute` reservoirs from whichthe water is expressed by the pressure of the inking-roller, so that thewater deposited by the dampingrollers, instead of being displaced orforced off from the non-printing or open surfaces by the pressure of theinking-roller, is held in reserve (No model.)

to be expressed and caused to liow over the non-printing surfaces whenthe inking-roller passes over said surfaces.

My invention also consists in applying a 5 5 backing of copper to thezine plates for the purpose of strengthening the plate and protecting itagainst the chemical action of certain absorbents of water which may beenr ployed, as hereinafter described.

Of the accompanying drawings, forming a part of this specification,Figure l represents a face view of an etched zinc plate embodying myinvention. Fig. 2 represents an enlarged section on line x x, Fig. 1.Figs. 3 and 4 rep` 65 resent views of a modification.

The same letters of reference indicate the same parts in all thefigures.

In carrying out my invention I prepare a Zinc plate for printing byapplying a design 7o thereto, etching to depress or eat away the surfacebetween and around the lines, any of the well-known and usual methods ofapplying the design and etching the plate being ernployed. 7 5

In the open surface between and around the lines of the design I formsmall perforations or reservoirs, which may be made by drilling orpunching through the plate to form independent oriiices a at any desireddistances 8o apart, or by forming the zinc plate on a backing of copperwire-cloth, as hereinafter described.

To the back of the perforated plate I apply a suitable absorbent, whichenters or communicates with the orifices, and 'is adapted to hold waterand yield the same when pressure is exerted upon the plate, as by theinkingroller, said pressure causing the water to ooze in smallquantities from the orifices upon the 9o surrounding surfaces of theplate. I prefer to employ glue as said absorbent, a coating of the glueof any desired thickness being applied to the back of the plate andconfined by sheets of papers or any other suitable material applied tothe back of the coating. The glue preferably projects into theperforations and partially fills them. A part of the water applied tothe plate, as usual, by the dampingrollers, which are passed over theplate before 10o the inking-rollers, enters the orifices, and is whollyor partially absorbed by the glueh When the inking-rollers pass over`the plate, their pressure causes the Water to exude from .the saturatedglue and spread thinly over the surrounding surfaces of the plate, thuseffectually protecting said surfaces from the ink, the inking-rollersbeing unable to sweep the Water from the plate by their rolling actionin consequence of the reserve-suppl y oozing from the orices.

This improvement enables Zinc plates to be used for work which hashitherto been performed only by lithographic stones, and thus a greatsaving in cost is effected.

The zinc plates may be applied to cylinders in cylinder-presses, whichis obviously impossible With lithographie stones.

I prefer to mix chrome alum with the glue to harden it and keep it frombeing dissolved too freely by the action of the Water. I do not limitmyself, however', to glue as an absorbent, as other materials may beused which may be proved suitable. Asphaltuln may be found desirable,and I contemplate using potters clay in some cases. A layer of felt orother suitable textile fabric may be used; but more care .would berequired in using it, because of its liability to absorb and give outWater too freely.

I prefer to coat the bacl; of the Zinc plate With copper byelectro-deposition, for the purpose of strengthening the plate andproventing it from cracking, and also to prevent chemical action of thechrome alum in the glue on the zinc plate. The face of the plate isprotected by a suitable coating While the back is being coppered. Afterthe plate is etched the open spaces around the printing lines orsurfaces may be thinly coated With copper,either by electro-depositionor mechanical precipitation, to form a surface which willv not receiveprinting-ink so readily as zinc, the smallest practicable quantity ofcopper being applied, so that the face of the plate will not beappreciably raised.'

The reservoirs may be formed by securing a zinc plate to a sheet ofcopper Wire-cloth and etching the plate to remove all the zincsurrounding the printing-surfaces, thus exposing the wire-cloth. y

The absorbent is applied to the back of the Wire-cloth, and the meshesof the latter constitute reservoirs, which are equivalents of theindependent orices above described. Fig. 3 shows a front view of aportion of a plate thus formed, and Fig. 4 au enlarged section on line yy, Fig. 3.

I claiml. A zinc plate prepared for printing and provided withperforations or reservoirs in its open spaces, as set forth.

2. A zinc plate prepared for printing andprovided with perforations orreservoirs in its open spaces, and with an absorbent of Water in orcommunicating with said reservoirs, as set forth.

3. A zinc plate prepared for printing and provided with perforations orreservoirs in its open spaces, and with a backingfof glue, as set forth.l

4. A zinc plate prepared for printingv audigy@- JOHN YV. BARRON.

Vitnesses:

C. F. BROWN, A. L. `WHITE.

